Physiological and biochemical responses of different shell color strains of Manila clam to low salinity challenges

Salinity is one of the important factors affecting geographic distribution, reproduction and physiological processes of marine and estuarine organisms. In this study, the effects of different salinity on the physiological and biochemical response were evaluated in three shell color strains and wild population of Ruditapes philippinarum by measuring superoxide dismutase (SOD), catalase (CAT), and alpha-amylase enzyme activity. With decreasing salinity, the SOD activity of wild clams, Zebra strain and White zebra strain increased firstly and in wild clam it decrease later, while the SOD activity of white clams firstly decreased and then increased. With decreasing salinity, the CAT activity of wild clams decreased first and then increased, while the zebra clam and white zebra clams increased first then decreased and white clams decreased The amylase in different strains of clams showed the same trend with decreasing first and then increased. The levels of amylase activities firstly decreased and then increased with the decrease of salinity in Manila clams. A similar trend of amylase activities were observed in different shell color strains and wild population of Manila clam. Our results may be used to optimize the salinity conditions for optimal growth and survival of R. philippinarum and to provide basic information for aquaculture management of this economically important bivalve species.